2.5m parts some extra's/changes needed

[Carl]

I've graduated to 2.5m parts now in my current career and quite a few issues are showing IMO.

 

1. There are a number of parts that for varying reasons are locked surprisingly deep in the tech tree that 2.5m designs have quite a few vital uses for yet don't really become available till the same tier as late 2.5m parts.

 

Sepetrons are by far the worse of these. 2.5m decouplers are just irredeemably bad at separating 2.5m assemblies. Yet Sepetrons are the same tier as mainsails and twin boars.

Larger RCS tanks, 2.5m designs and even the 1.25m tanks are all buried at the mainsail tier again. Spread these out through different researches at more appropriate tiers would be very helpful.

Batteries. Whilst the batteries we get are technically adequate for needs at their tiers they arrive at the forms factors are problematic. When your using 1.25m service bays, putting a stack of 0.625m batteries in the bay with radically attached square batteries is adequate, at 2.5m scale it's less ideal as you waste more of the bays volume. I also don;t like how unlike reaction wheels they don;t stack neatly in the bay, the top/bottom most one will allways clip.

 

 

 

2. A lack of several forms of 2.5m part.

 

Parachutes are the big problem, specifically radial chutes. The existing 1.25m designs work upto about the payload limit of 1.25m parts, and for smaller 2.5m payloads they work fine too. but get to medium or large 2.5m payloads and you start having to plate things in chutes to get them to come back down ok. Having some proper 2.5m chutes with the correspondingly fewer parts, better performance, and likely lower craft surface area utilization would be brilliant.

The other issue is SRB's, the Flea has allways been a bit of a novelty item, but the hammer and especially humper have become staples of my liftoff 1.25m stages, being used to lift my 1.25m liquid boosters those first few km upwards. But once i graduated to 2.5m designs i started to have real issues using them like that, even the mighty kickback lacks the thrust to lift 2.5m stages unless it's multiple per 2.5m stack, and when you have radially mounted 2.5m stacks thats just a real pain in layout, stability, and especially part count. I'd really like to see some 2.5m versions of the existing 1.25m designs which are just 4 of the 1.25m models packaged into a single slightly longer fuselage.

I also suspect i'm going to find similar issues with RCS, chutes,boosters, e.t.c at the 3.75m size.

 

Errr i'm sure i had a point 3 but it's escaping me now. So thats it for now.

 

Edited January 3, 2017 by Carl

[GluttonyReaper]

3 hours ago, Carl said:

I also suspect i'm going to find similar issues with RCS, chutes,boosters, e.t.c at the 3.75m size.

You have no idea...

But anyway, for 2.5m parts, I'm generally not that concerned tbh. Bigger seperatrons and SRBs would be very nice though, and stack seperators should be available with docking ports imo.  

Edited January 3, 2017 by GluttonyReaper

[Carl]

Well to be fair, i'd prefer it is sepetrons where integrated into decouplers. It would make getting rockects at 2.5m scale to come apart so much better.

[Speeding Mullet]

7 hours ago, Carl said:

but the hammer and especially humper have become staples

The issue I have with career is more that I unlock everything so quickly that the tech tree sort of becomes pointless beyond a couple of missions at the start where you are working around the issues that you are describing with brute force and cheap tricks.  With that in mind I'd agree that it's still not right as a game function over all, but career mode has certainly improved a lot since it was introduced.  I'm not here to speculate on how to improve it, as I'm mostly a sandbox player, but I can provide some point of view and possibly a work around or two on a couple of your other irks:

2.5m decouplers - I've never had an issue.  You can tweak the separation force which helps a lot.  On the smaller craft I often use a much reduced force, and on most craft I break down the decouple and next stage engine into separate stages to provide some separation time.  Once you do get sepatrons you can embed them inside the decouple ring if that makes sense for a little extra "go" on separation.

RCS - Again never had an issue with this really.  Most of my craft use no RCS unless I'm docking, building an SSTO, or flying an enormous payload.  Even SAS wheels are mostly redundant for me once the pods with built in SAS become available.  A well balanced craft really should need minimal input of both.  I sometimes get guilty of wanting everything to happen in 3 seconds, but it's space, and there's often much time to complete manoeuvres so I've got used to slowing things down.  Less RCS/SAS = more payload

Batteries - Same story as RCS unless you are mining really.  You can pretty much get away with 1 battery and 1 solar panel for a lot of mission types.  I always go totally overboard in the name of aesthetics, so I learnt to get creative with the placement of these things.  Check out the craft aesthetics thread for some great hints and tips on efficiency and beautiful design.

Undesirable clipping - Hit up against this all the time my friend.  Simply use the tweaking tools to move the part around until you reach the desired clip / no clip

Parachutes - Landing the heavy stuff hey!  Use a mix of powered landing and chutes.  At this stage (and not being harsh) the issue is with your craft design rather than the lack of parachutes, but I totally agree that a larger radial chute would be a great addition.  I don't think it should carry a smaller form factor unless they are a different, lighter, and more breakable material though.  If you are feeling a little moddy the realchutes might be a good pickup for you as this is not likely to be addressed.

SRB's - See previously mentioned aesthetic thread for some great ideas on clustering for more power, but I'm absolutely with you about needing a larger diameter SRB.  I tend to use the SRB's as augmenters rather than anything else so generally find a couple of kickbacks with a LF engine in the middle work fine for me.  By the time the kickbacks are done the craft normally has plenty of height and downrange speed for the smaller engine to make the rest of the journey.  If you are building big with 2.5m parts then yep, some of my rockets also become SRB fests, but that's half the fun - I sometimes play for realism with my rockets, but once I start launching things like Cathedrals to the mun (yep I did that) then I'm fine with everything becoming a little silly as a result.

3.75m parts - Properly balanced and designed you really won't see much of an issue, but I'd agree that things seem to fragment a little at this end of the scale with more propensity for spamming things like landing legs, RCS, chutes etc etc.

Other solutions - I guess, um, mod the hell out of it   Seriously though if you aren't opposed to modding then this is the way forwards for you.  If you want to play stock only then I fully appreciate that - I for one enjoy playing stock and massively modded games both, but I guess in lieu of these parts actually being in the stock game I've just been playing long enough to develop my own, or copy others workarounds.  Totally awesome to be making suggestions though!!

 

I also insist that the proposed new 2.5m SRB be named the Humper

SM

[Carl]

1 hour ago, Speeding Mullet said:

The issue I have with career is more that I unlock everything so quickly that the tech tree sort of becomes pointless beyond a couple of missions at the start where you are working around the issues that you are describing with brute force and cheap tricks.  With that in mind I'd agree that it's still not right as a game function over all, but career mode has certainly improved a lot since it was introduced.  I'm not here to speculate on how to improve it, as I'm mostly a sandbox player, but I can provide some point of view and possibly a work around or two on a couple of your other irks:

2.5m decouplers - I've never had an issue.  You can tweak the separation force which helps a lot.  On the smaller craft I often use a much reduced force, and on most craft I break down the decouple and next stage engine into separate stages to provide some separation time.  Once you do get sepatrons you can embed them inside the decouple ring if that makes sense for a little extra "go" on separation.

RCS - Again never had an issue with this really.  Most of my craft use no RCS unless I'm docking, building an SSTO, or flying an enormous payload.  Even SAS wheels are mostly redundant for me once the pods with built in SAS become available.  A well balanced craft really should need minimal input of both.  I sometimes get guilty of wanting everything to happen in 3 seconds, but it's space, and there's often much time to complete manoeuvres so I've got used to slowing things down.  Less RCS/SAS = more payload

Batteries - Same story as RCS unless you are mining really.  You can pretty much get away with 1 battery and 1 solar panel for a lot of mission types.  I always go totally overboard in the name of aesthetics, so I learnt to get creative with the placement of these things.  Check out the craft aesthetics thread for some great hints and tips on efficiency and beautiful design.

Undesirable clipping - Hit up against this all the time my friend.  Simply use the tweaking tools to move the part around until you reach the desired clip / no clip

Parachutes - Landing the heavy stuff hey!  Use a mix of powered landing and chutes.  At this stage (and not being harsh) the issue is with your craft design rather than the lack of parachutes, but I totally agree that a larger radial chute would be a great addition.  I don't think it should carry a smaller form factor unless they are a different, lighter, and more breakable material though.  If you are feeling a little moddy the realchutes might be a good pickup for you as this is not likely to be addressed.

SRB's - See previously mentioned aesthetic thread for some great ideas on clustering for more power, but I'm absolutely with you about needing a larger diameter SRB.  I tend to use the SRB's as augmenters rather than anything else so generally find a couple of kickbacks with a LF engine in the middle work fine for me.  By the time the kickbacks are done the craft normally has plenty of height and downrange speed for the smaller engine to make the rest of the journey.  If you are building big with 2.5m parts then yep, some of my rockets also become SRB fests, but that's half the fun - I sometimes play for realism with my rockets, but once I start launching things like Cathedrals to the mun (yep I did that) then I'm fine with everything becoming a little silly as a result.

3.75m parts - Properly balanced and designed you really won't see much of an issue, but I'd agree that things seem to fragment a little at this end of the scale with more propensity for spamming things like landing legs, RCS, chutes etc etc.

Other solutions - I guess, um, mod the hell out of it   Seriously though if you aren't opposed to modding then this is the way forwards for you.  If you want to play stock only then I fully appreciate that - I for one enjoy playing stock and massively modded games both, but I guess in lieu of these parts actually being in the stock game I've just been playing long enough to develop my own, or copy others workarounds.  Totally awesome to be making suggestions though!!

 

I also insist that the proposed new 2.5m SRB be named the Humper

SM

As i noted, small 2.5m i think works fine. The thing with batteries is more an OCD thing, i end up with a 2.5m service bay with a piddly littile stack of 0.625m batteries in it and no other use for it, grates at the waste in space drag and other stuff.

 

RCS is dependent on scale, i'm building designs lifting roughly a 100 tons to orbit, you need several hundred monoprop to dock one of those even with MJ's near perfection in that regard.

 

Chutes: i'm talking getting back down to kerbin, again try to bring a dozen tons down, bearable, try to get a 24 ton hab module tourist stack down and you start having to plate it in chutes, powered descent isn't somthing i'd every try or consider worth it on kerbin.

 

See this for chutes and SRB's for example. Whilst i've since improved the lifter in several ways and found i can bring this particular stack down tail first, (i just moved the heat shield), without it flipping and burning up at highest altitudes, just look at the chutes needed to get it down. likewise look at the combo liquid/solid setup i had to use, i'd prefer much more to just build an enlarged 2.5m version of this 1.25m design. But the SRB's won't hack it. And all thats without adding RCS to get it to dock with anything.

Edited January 3, 2017 by Carl

[Red Iron Crown]

2 hours ago, Carl said:

As i noted, small 2.5m i think works fine. The thing with batteries is more an OCD thing, i end up with a 2.5m service bay with a piddly littile stack of 0.625m batteries in it and no other use for it, grates at the waste in space drag and other stuff.

RCS is dependent on scale, i'm building designs lifting roughly a 100 tons to orbit, you need several hundred monoprop to dock one of those even with MJ's near perfection in that regard.

Seems like you could solve these two simultaneously, put a bunch of radial RCS tanks in the service bay.

Definitely agree about the desirability of a 2.5m SRB, clusters of Kickbacks eat at the part count too much for some things.

[StrandedonEarth]

3 hours ago, Carl said:

RCS is dependent on scale, i'm building designs lifting roughly a 100 tons to orbit, you need several hundred monoprop to dock one of those even with MJ's near perfection in that regard.

MJ? Near perfect? I seem to recall hearing MJ was more to the wasteful side of monoprop usage, but I wouldn't know because I've never used it. Not that there's anything wrong with using it. More to the point, I almost never use monoprop anymore except for the smallest craft; vernors all the way man! If they're too strong for your ship then use capslock to reduce and help balance the thrust. 

3 hours ago, Carl said:

Chutes: i'm talking getting back down to kerbin, again try to bring a dozen tons down, bearable, try to get a 24 ton hab module tourist stack down and you start having to plate it in chutes, powered descent isn't somthing i'd every try or consider worth it on kerbin.

You don't have to do a full powered descent on Kerbin; if you don't want to slap enough chutes on then you could just do a Soyuz-style short burn just before touchdown to bring your descent speed within safe limits.

But yeah, 2.5m SRB's and maybe some inline chutes would be nice. I get by with inline batteries, but I'm not averse to just slapping some square BattMans on the side if that's all I have. But then, I take a perverse delight in building ugly.

[Speeding Mullet]

37 minutes ago, Red Iron Crown said:

Seems like you could solve these two simultaneously, put a bunch of radial RCS tanks in the service bay.

Plus goo canisters, and all the other science bits - Has always packed out the space for me in career mode!

 

3 hours ago, Carl said:

RCS is dependent on scale, i'm building designs lifting roughly a 100 tons to orbit, you need several hundred monoprop to dock one of those even with MJ's near perfection in that regard.

for a hundred ton payload the amount of monoprop you need should still be small, sometimes vanishingly small if you are practiced enough in docking.  this post made by @Snark yesterday eludes to that, although doesn't put a figure on the amount of monoprop Snark would use for say a 100, 200, 500t docking manoeuvre.  Perhaps Snark can furnish us with a figure or two?

Yesterday I flew a 45t SSTO to a 200km orbital research post, and used 25 monoprop in what I would consider to be an incredibly wasteful docking manoeuvre.  I then went on flybys past Mun, Minus, and 3 aerobraking manoeuvres, and a re-entry using only 90 monoprop, and still didn't run out.  Balance, and efficiency in design and you will need hardly any of the stuff.  This will only come with practice I'll admit, but practice makes perfect

 

3 hours ago, Carl said:

Chutes: i'm talking getting back down to kerbin, again try to bring a dozen tons down, bearable, try to get a 24 ton hab module tourist stack down and you start having to plate it in chutes, powered descent isn't somthing i'd every try or consider worth it on kerbin.

As @StrandedonEarth and I both mentioned, a mix of chutes and powered landing is what we are talking about.  Given the Soyuz as a real life example of mixed landing, and the future Space-X command pod (Dragon V2) landing on Super Dracos when finished (not to mention the first stage powered landing) then I'm not sure why you wouldn't consider it worth it.  You will use remarkably little fuel and engine doing a mixed landing, than just spamming parachutes onto really heavy objects.  There will come a weight I'm sure (citation needed) where it is more efficient to conduct a mixed landing rather than relying on just chutes.

 

3 hours ago, Carl said:

See this for chutes and SRB's for example.

Yep well you are in silly rocket territory there, but this is a good case for larger SRB's no doubt!  I reckon you could cut about half of your drogue chutes out and replace them with fewer main chutes to get less spamming, but this is a prime candidate for a parachute and retro-propulsive landing.  You've maybe got upwards of 4t of parachutes on that bad-boy, most of which could be replaced with a retro-propulsive landing system for likely little or no extra cost in mass or cash.

 

3 hours ago, Carl said:

i'd prefer much more to just build an enlarged 2.5m version of this 1.25m design. But the SRB's won't hack it.

Yep another good reason for having larger SRBs for sure!

SM

[Snark]

18 minutes ago, Speeding Mullet said:

for a hundred ton payload the amount of monoprop you need should still be small, sometimes vanishingly small if you are practiced enough in docking.  this post made by @Snark yesterday eludes to that, although doesn't put a figure on the amount of monoprop Snark would use for say a 100, 200, 500t docking manoeuvre.  Perhaps Snark can furnish us with a figure or two?

Well, it's small enough that I've never bothered to track it. 

I generally put on a couple of the smallest radial monoprop tanks ('coz that's the smallest thing the stock game has; need two of 'em for symmetry), which have a max capacity of 60 units apiece.  Often I'll leave them half-empty, because 120 units is far more than I need.

So I generally carry no more than ~60 units of monoprop for even the biggest ships, and that's way more than I need-- enough for many docking cycles.

4 hours ago, Carl said:

RCS is dependent on scale, i'm building designs lifting roughly a 100 tons to orbit, you need several hundred monoprop to dock one of those even with MJ's near perfection in that regard.

"Several hundred" is way more than necessary, by orders of magnitude.

Just doing it by the math:  100-ton ship, RCS thrusters at Isp 240, you use 0.3 m/s of dV to dock once.  Doing the math, that works out to be 12.7 kg of monoprop, which is just over 3 units.  Sounds about right to me.

So, about 3 units of monoprop per 100 tons of ship, for each docking cycle.

[Carl]

Mullet first, it's a limited tech design, the best i could put on there for a powered descent would weigh vastly more, (thuds a a rockermax quarter tank). But i'm still not convinced you would get it down on less even with better tech. My experiance is that despite what the temp tolerance says you need to get the reentry velocity down a lot more for engines if you want to bring them down with you. It's probably their size. Also it comes back to another key point. I'm much more a builder than a pilot. I tend to build with roughly 3 thoughts in mind:

 

 

 

1. Always overestimate your estimates. Better to have a rocket a bit more capable than it need to be than have something go wrong and then come up short.

 

2. Make it as foolproof as possibble. If i miss time or otherwise screw up my estimated landing burn i want it to handle coming down on a 45 degree mountainous slope, or clipping the command pod on the top of the VAB or whatever.

 

3. What's going to be the easiest to automate or make require minimal input.

 

As long as you get 1 and 3 right, 2 tends to follow on it's own though.

 

The thing with a powered descent with chute assist is that it takes a lot of dv to give good safety margins. Also short burns are hard to time even though a few chuts and a pair of sepetrons could theoretically do it. And again if you want it proof against foolishness you really need several carefully balanced engines and a good bit of dv to pull it off.

 

Don;t get me wrong, Duna i'd absolutely use a powered decent, the atmosphere just isn't thick enough for chutes alone, and given the engine stack i'd be dropping a chute/power combo on eve would probably make some sense, (not sure about elsewhere, forget what the others atmosphere is like).

 

 

Regarding RCS, oh if your willing to use super piddly d/v numbers and takes ages to dock you can do it with very little monoprop. I prefer peak velocities of about 0.5 m/s. With 3 axs and acel/decel that adds upto 3m/s dv needed, or for a 115 ton design like i was messing with yesterday, 360ish monoprop.Call it 400 to be safe. Accounting for undocking and a further safety margin/provision for other stuff, call it a full 2.5m tank at 780 monoprop.

The point i'm getting at is the only monoprop you get before the mainsail tier is the little radial spherical tanks. That just dosen;t make any sense to me that the bigger radials or the 1.25m tanks are locked till then, 2.5m is a bit more understandable but still eh.

 

 

 

[Shadowmage]

22 hours ago, Carl said:

RCS is dependent on scale, i'm building designs lifting roughly a 100 tons to orbit, you need several hundred monoprop to dock one of those even with MJ's near perfection in that regard.

From my experiences in prior versions MJ is quite horrendous at docking efficiently.  It can generally get the job done, but where MJ might use 20-40 units of MP to dock a small craft, I can usually get by with <2 (and often zero MP/RCS use).  Not sure if this has changed in recent MJ versions (haven't used it since KSP 1.05), and even back then the level of efficiency you got out of it depended mostly on having a well balanced craft.

Manual docking, with little to no RCS use -- Zero relative thrust with main engine at <100m from target (not close to, but actually -zero-, use thrust limiter....).  Point at target, make target point at you, use main engine to gently nudge at ~0.5m/s forward speed, and just let things dock; RCS is only needed for very fine trajectory adjustment during the <100m approach, and depending on orbits, often not needed at all (higher gravity/faster orbits perturb the approach faster).  It gets slightly more complex if your target can't rotate to point at you (very large station, unmanned/uncontrolled fuel depot, debris, etc), in which case you need to use the main engine to place yourself in a position in space ~100m on a direct line out from the port you want to dock with (the rest of the steps stay the same).  If you are using more than a few (2-5) units of MP per 100 tons when docking manually then there is likely much room for improvement in your methods.

Note, the above is using main engines for many of the 'maneuver' burns and only using actual RCS for the fine-tuning of the final approach.  If you don't use the main engine for the maneuver burns your RCS fuel usage will go up considerably, but should still only be a few (<10) dV worth of RCS needed total.
The only time I've used the actual RCS fuel tanks were for craft designs that used the puff mono engines; all other times the fuel included in the pod or a pair of small radial tanks is sufficient for many, many dockings. 
I also no longer use MJ to dock for me; when I first started it was a crutch that I used all the time; now it is always faster and more efficient for me to dock manually (though I do use MJ's SAS features for alignment on the final approach).

-- Practice, practice, practice.

[Carl]

@Shadowmage Mj can be velocity limited, it used to be bad because it would max velocity going in out,. Now you can limit it so as long as it doesn't need to go clean around or somthing your total monoprop usage is 6 time the velocity limit times the monoprop per m/s of dv. The thing is monoprop is a little under 1m/s (0.96 to be precise), per ton of spacecraft per 1 unit of monoprop. a 3 axis translation with a velocity cap of 0.5m/s needs 3m/s of dv which for a 100 ton spacecraft is 312.5 monoprop. Your right if you can align everything before hand and just use a main engined nudge you'll be fine with nearly no monoprop. Want to actually do full 3 axis translation docking under RCS you'll go through a fair bit.

Edited January 4, 2017 by Carl

[Speeding Mullet]

9 hours ago, Carl said:

Mullet first, it's a limited tech design

Can you post your tech tree?  I'd like to have a go with the limitations you are facing and the same payload (share the craft file if you can).  Even just to prove myself wrong it would be interesting!

SM

[Shadowmage]

15 minutes ago, Carl said:

@Shadowmage Mj can be velocity limited, it used to be bad because it would max velocity going in out,. Now you can limit it so as long as it doesn't need to go clean around or somthing your total monoprop usage is 6 time the velocity limit times the monoprop per m/s of dv. The thing is monoprop is a little under 1m/s (0.96 to be precise), per ton of spacecraft per 1 unit of monoprop. a 3 axis translation with a velocity cap of 0.5m/s needs 3m/s of dv which for a 100 ton spacecraft is 312.5 monoprop. Your right if you can align everything before hand and just use a main engined nudge you'll be fine with nearly no monoprop. Want to actually do full 3 axis translation docking under RCS you'll go through a fair bit.

3.06m/s for a 100t spacecraft is only ~0.12t (120kg) of monopropellant @ 260 ISP  ( http://www.strout.net/info/science/delta-v/ ).  Using the 4kg/unit given on the KSP wiki for density ( http://wiki.kerbalspaceprogram.com/wiki/Monopropellant ), you would need ~30 units of MP  (30units * 4kg/unit = 120kg).

What math is giving you a need for >300 units of MP? 

(Not trying to argue on the best way to dock (engine vs rcs), merely trying to figure out where the differences in thinking / opinion / math are occuring).

[fourfa]

I use MechJeb for docking sometimes, and it's terrible with RCS.  Manually I use a blip here, a blip there, a good bit of patience, and barely touch the monoprop supply.  Activate MechJeb's docking mode though, and all of a sudden it goes "BLAHHHHHHHH FIRE ALL THE RCS ALL THE TIME" and hemorrhages through the supply quite rapidly.  At least 10X the rate I'd say, probably more?

I use a Module Manager script to deactivate all rotation thrust from all RCS thrusters ever, always (info here).  If you haven't done that, and are spraying monoprop every time you want to turn (ie bone stock), you will definitely observe higher RCS usage.  I bet many of the people responding here are forgetting that stock reaction controls waste tons of monoprop.

The only time I ever use RCS rotation is when I'm feeling masochistic and want to fly a real-life-style mission with zero reaction wheels, only RCS.  Man, that will reset your expectations of orbital precision. And if you don't use RCS Build Aid, you will hate life.

[Carl]

Quote

Can you post your tech tree?  I'd like to have a go with the limitations you are facing and the same payload (share the craft file if you can).  Even just to prove myself wrong it would be interesting!

SM

Moved on since then but i can try to reconstruct for you from memory, may have a save actually.

9 hours ago, Shadowmage said:

3.06m/s for a 100t spacecraft is only ~0.12t (120kg) of monopropellant @ 260 ISP  ( http://www.strout.net/info/science/delta-v/ ).  Using the 4kg/unit given on the KSP wiki for density ( http://wiki.kerbalspaceprogram.com/wiki/Monopropellant ), you would need ~30 units of MP  (30units * 4kg/unit = 120kg).

What math is giving you a need for >300 units of MP? 

(Not trying to argue on the best way to dock (engine vs rcs), merely trying to figure out where the differences in thinking / opinion / math are occuring).

Possible i'm messing up the equations, been a while since i had to touch them. I thought it was (mass of rocket * dv)/ISP = Fuel mass used. need to look them up, been waaaay too long.

 

Quote

I use MechJeb for docking sometimes, and it's terrible with RCS.  Manually I use a blip here, a blip there, a good bit of patience, and barely touch the monoprop supply.  Activate MechJeb's docking mode though, and all of a sudden it goes "BLAHHHHHHHH FIRE ALL THE RCS ALL THE TIME" and hemorrhages through the supply quite rapidly.  At least 10X the rate I'd say, probably more?

I use a Module Manager script to deactivate all rotation thrust from all RCS thrusters ever, always (info here).  If you haven't done that, and are spraying monoprop every time you want to turn (ie bone stock), you will definitely observe higher RCS usage.  I bet many of the people responding here are forgetting that stock reaction controls waste tons of monoprop.

The only time I ever use RCS rotation is when I'm feeling masochistic and want to fly a real-life-style mission with zero reaction wheels, only RCS.  Man, that will reset your expectations of orbital precision. And if you don't use RCS Build Aid, you will hate life.

Use a reasonable velocity limit and disable rotation and it won't do that. ure if you set it to like 10m/s or something silly it will do that, but thats extreme even by my standards.

Edited January 5, 2017 by Carl

[Carl]

Ok defintly messed up the sums, got to go soon, workmen coming, but at 240 ISP a quad is giving 9.4 m/s of dv per 4kg of fuel used per ton of spacecraft.

[Carl]

This should be the tech tree i had when i built that craft. Note no real RCS at the time. RC testing was done in sandbox with a variant design.

 

 

Craft file is in the OP of the spacecraft exchange thread here. Note that i made a couple of edits to that at one point, changed the heatshield to bottom of stack and reduced batteries in the battery bay. I haven't got round to updating the thread version though.

Edited January 5, 2017 by Carl

[Speeding Mullet]

12 hours ago, Carl said:

Craft file is in the OP of the spacecraft exchange thread here

Cool I'll have a crack this weekend and see what I can come up with!

SM

[Carl]

Cheers, i updated the linked threads craft file to the later version btw, note the point about not doing an aerobrake from mun, 3kps+ is too high an entry velocity for this. Get to down to at least 2.5kps.

[Whisky Tango Foxtrot]

Question for the people trying to dock giant ships with RCS: If your ships are that big, why don't you just put some Vernor thrusters on them and cut out the monopropellant entirely?

[Speeding Mullet]

On 1/6/2017 at 9:55 AM, Carl said:

Cheers, i updated the linked threads craft file to the later version btw, note the point about not doing an aerobrake from mun, 3kps+ is too high an entry velocity for this. Get to down to at least 2.5kps.

OK I had a look at this from the point of view of the return vehicle only.  Didn't bother messing around with the lift vehicle, but I'm pretty sure there is efficiency to be made there.  I got your parachutes down from nearly 40 to just 2 drogues and 1 main, removed the 2 large reaction wheels and replaced them with 1 medium one, which in turn removed the need for one of the cargo bays.  got rid of 2 of the solar panels (2 is still too many) and half the batteries (still too many).  I added an assisted landing system to take the speed from 24m/s under fully deployed parachutes to under 4.5 m/s at landing, and added 6 landing legs for stability.  I also removed all your monoprop, added some stabilisation fins, lights, and a vernor system to help stabilise during re-entry.  I aero-braked from beyond Minmus and then re-entered with no issues despite cutting the ablator from 800 to 400 units and landed on a relatively steep hill with LFO to spare.

I did all this for a weight saving of 1.276t, and cost saving of 10,786 

Gallery here

Hooray for power assisted landings!

SM

[Carl]

Ok

 

1. How are you controlling the upper stage with that few reactions wheels. You have nowhere near enough torque. it should take you somthing like a minute to complete a significant rotation. I'm actually on the verge of adding more 2.5m reaction wheels to the design because on actual mun missions i'm finding it lacks enough torque.

 

2. I use 4 solar panels so i don't have to worry about them being edge on. it's way more than needed but it gets the job done which is what matters.

 

3. Thats not a steep hill, thats a flat plain. Try putting it down in the drink or on the mountains to the west of KSP, (usually where it comes down after my inevitable over/undershoot). Thats why i bring long stacks down side on, if i land them on their base they will topple if they hit those mountains or the water, and then they explode.

 

4. I don't call that spare fuel, your on dregs.

 

Don't take this the wrong way but this is a great example of powered landings doing what i said it actually did well just fine. But a terrible example of it doing what my design could allready do that i felt a power assisted landing couldn't do. I.e. put the design down on it's side even in spite of steep terrain or brushing against a mountain side/KSC building a hundred meters off the ground, and doing all that without much if any input from me.

 

Your design is basically engineered to require a very good pilot who can time that final burn precisely, (because no spare fuel), and never puts it down on a steep slope, and is willing to put up with all the time compromises on the upper stage and never forgets to roll ship to expose the panels, and so on and so forth.

 

I design so a complete dunce capable of following only the most basic of instructions and doing all kinds of unwise things and mistiming nearly everything can fly the design and get it down safely. I also design to keep time frames on anything down.

 

I mean it's still a cool redesign, but it msises probably the biggest core part of the design of the original, namely the side on landing.

Edited January 7, 2017 by Carl

[MaxL_1023]

SpaceY has a lot of the parts you would need - Lithobrake also has large parachutes as well. I find that the stock game is more of a base platform - it is not intended to do anything with 100 ton ships. You have graduated beyond what Squad could reasonably design for without making so many parts that new players are overwhelmed. 

I rarely use solids unless I have major part count or cost issues - liquid fueled boosters are better. I would like to see a stock version of the Pyrios booster - basically a twin boar with another tank and nose cone on top of it, compressed into one part. The twin boar itself is useful but it still has the part count problems when you need other tanks, struts, etc. 

A 2.5m SRB might fit in stock, but it would be wasteful in terms of mass and efficiency compared to liquid fueled boosters. 

[Red Iron Crown]

7 minutes ago, MaxL_1023 said:

A 2.5m SRB might fit in stock, but it would be wasteful in terms of mass and efficiency compared to liquid fueled boosters. 

Cost efficiency is a thing, though.